WinRegisterClass

WinRegisterClass

WinRegisterClass( hab, pszClassName, pfnWndProc, flStyle, cbWndData );

Usage Explanation

This API is normally used by the main window of all applications. Its main purpose is to register the address of the window procedure for this class. After this has been done, WinCreateWindow or WinCreateStdWindow can be used to create windows of this class, usually the main window of the app.

The private class name must not clash with the name of a public class in the same process. If this should happen, FALSE will be returned, and PMERR_PARAMETER_OUT_OF_RANGE will be returned from WinGetLastError. A private class can override an older private class, though, in which case the current parameters replace the old ones.

Private classes disappear when the owning process terminates, ie. when they are no longer needed.

Parameters

HAB hab (input)

Anchor block handle.

PSZ pszClassName (input)

The name of the class to register. This is usually specific to your application.

PFNWP pfnWndProc

The window procedure of the application.

ULONG flStyle

Default window style. This is the default style of any windows created of this class. This can be modified in the usual manner. If CS_PUBLIC is specified, any process can use this public class. Otherwise, a private class is created, available only to this process. You must only specify CS_PUBLIC for the shell process. This value is frequently 0L.

CS_CLIPCHILDREN	Clip window drawing to children's boundaries
CS_CLIPSIBLINGS	Clip window drawing to siblings' boundaries
CS_FRAME	Frame window
CS_HITTEST	When pointer is in window, WM_HITTEST is sent
CS_MOVENOTIFY	WM_MOVE messages will be sent to window
CS_PARENTCLIP	Clip window drawing to parent's boundaries
CS_PUBLIC	Makes the new class public (see above)
CS_SAVEBITS	Save area covered by window for faster redraws
CS_SIZEREDRAW	Invalidates whole window when it is resized
CS_SYNCPAINT	Window is repainted synchronously (WM_PAINT is SENT)
...	Other Control Styles

ULONG cbWindowData

The number of bytes reserved for storage for each window of this class which is created. If none is needed, specify 0L.

Returns

BOOL retval

TRUE means class was registered. FALSE means it was not. If FALSE is returned, you may use WinGetLastError() to find out what went wrong. Possible errors are:

0x1003	PMERR_PARAMETER_OUT_OF_RANGE	A parameter was out of range (?).
0x1013	PMERR_INVALID_HATOMTBL	An invalid atom table handle was passed.
0x1015	PMERR_INVALID_ATOM_NAME	An invalid atom name string was given.
0x1016	PMERR_INVALID_INTEGER_ATOM	The atom specified is not a valid integer atom.
0x1017	PMERR_ATOM_NAME_NOT_FOUND	The atom name given was not in the atom table.
0x1019	PMERR_INVALID_FLAG	An invalid bit was set for a parameter.
0x1208	PMERR_INVALID_PARAMETERS	One or more parameters were invalid.

Include Info

1. define INCL_WINWINDOWMGR
   #include <os2.h>

Gotchas

Only DLLs run by the shell at startup can use the CS_PUBLIC style.

Sample Code

#define INCL_WINWINDOWMGR
#include <os2.h> 

MRESULT EXPENTRY WndProc (HWND hwnd, ULONG msg, MPARAM mp1, MPARAM mp2); 

HAB hab;
HMQ hmq;
CHAR szClassName[] = "My_class";

hab=WinInitialize(0L);
hmq=WinCreateMsgQueue(hab, 0L);

if (hmq) {
   retval = WinRegisterClass(hab,
                             szClassName,
                             (PFNWP) WndProc,
                             0L,
                             0L);

  .
  .
  .
}

Related Functions

WinInitialize, WinCreateMsgQueue, WinCreateStdWindow, WinCreateWindow